The metalloprotein, Concanavalin A, requires the presence of transition metal and calcium ions before the protein adopts the active conformation which recognizes monosaccharides and polysaccharides having free hydroxyl groups at C3, C4, and C6 in the D-arabino - pyranoside configuration. The aggulatination of tumorous and chemically transformed cells by Con A is thought to result from intercellular crosslinking of cell surface glycoprotein receptors. Yet recent evidence suggests Con A may possess heterogeneous cell recognition sites which display allosteric behavior. Crystallographic studies have revealed a hydrophobic crevice in the protein where a variety of non-polar molecules bind in the solid state but have failed to identify those amino acids which create the specific sugar site. Several solution structural features of Concanavalin A will be studied by fluorescence energy transfer experiments, photoaffinity labeling, and high resolution carbon-13 nuclear magnetic resonance techniques. The spectral and magnetic properties of the lanthanides will be utilized to determine solution distances from fluorescence data and assign individual carbon resonances in the magnetic resonance experiments, respectively. The assigned single carbon resonances will be monitored to differentiate between simple sugar versus whole cell binding to Con A. These data will establish a general mechanism for lectin-whole cell interactions.